From 38aa34eae8e6aa8504f97f86ac155a0ebc6a0557 Mon Sep 17 00:00:00 2001
From: David Plowman <david.plowman@raspberrypi.org>
Date: Wed, 15 Jan 2020 13:40:38 +0000
Subject: [PATCH] media: ov5647: Fix return codes from
 ov5647_write/ov5647_read functions.

Previously they were returning positive non-zero codes for success,
which were getting passed up the call stack. Since release 4.19,
do_dentry_open (fs/open.c) has been catching these and flagging an
error. (So this driver has been broken since that date.)

Fixes: 3c2472a [media] media: i2c: Add support for OV5647 sensor
Signed-off-by: David Plowman <david.plowman@raspberrypi.org>
Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
---
 drivers/media/i2c/ov5647.c | 38 ++++++++++++++++++++++++++++++++------
 1 file changed, 32 insertions(+), 6 deletions(-)

--- a/drivers/media/i2c/ov5647.c
+++ b/drivers/media/i2c/ov5647.c
@@ -587,7 +587,13 @@ static int ov5647_write16(struct v4l2_su
 	int ret;
 
 	ret = i2c_master_send(client, data, 4);
-	if (ret < 0) {
+	/*
+	 * Writing the wrong number of bytes also needs to be flagged as an
+	 * error. Success needs to produce a 0 return code.
+	 */
+	if (ret == 4) {
+		ret = 0;
+	} else {
 		dev_dbg(&client->dev, "%s: i2c write error, reg: %x\n",
 			__func__, reg);
 		return ret;
@@ -603,10 +609,17 @@ static int ov5647_write(struct v4l2_subd
 	int ret;
 
 	ret = i2c_master_send(client, data, 3);
-	if (ret < 0) {
+	/*
+	 * Writing the wrong number of bytes also needs to be flagged as an
+	 * error. Success needs to produce a 0 return code.
+	 */
+	if (ret == 3) {
+		ret = 0;
+	} else {
 		dev_dbg(&client->dev, "%s: i2c write error, reg: %x\n",
 				__func__, reg);
-		return ret;
+		if (ret >= 0)
+			ret = -EINVAL;
 	}
 
 	return 0;
@@ -619,17 +632,30 @@ static int ov5647_read(struct v4l2_subde
 	int ret;
 
 	ret = i2c_master_send(client, data_w, 2);
-	if (ret < 0) {
+	/*
+	 * A negative return code, or sending the wrong number of bytes, both
+	 * count as an error.
+	 */
+	if (ret != 2) {
 		dev_dbg(&client->dev, "%s: i2c write error, reg: %x\n",
 			__func__, reg);
+		if (ret >= 0)
+			ret = -EINVAL;
 		return ret;
 	}
 
 	ret = i2c_master_recv(client, val, 1);
-	if (ret < 0) {
+	/*
+	 * The only return value indicating success is 1. Anything else, even
+	 * a non-negative value, indicates something went wrong.
+	 */
+	if (ret == 1) {
+		ret = 0;
+	} else {
 		dev_dbg(&client->dev, "%s: i2c read error, reg: %x\n",
 				__func__, reg);
-		return ret;
+		if (ret >= 0)
+			ret = -EINVAL;
 	}
 
 	return 0;
